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arXiv 1802.02864hep-phnucl-th
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规范不变Noether定理与质子自旋危机

Gauge Invariant Noether's Theorem and The Proton Spin Crisis

Gouranga C Nayak

摘要:

由于质子自旋危机,从第一性原理出发理解夸克和胶子的自旋和轨道角动量的规范不变量定义是必要的。本文用组合洛伦兹变换和定域规范变换导出规范不变量Noether定理。我们发现,在狄拉克-麦克斯韦理论中,虽然存在电子自旋(或轨道)角动量的规范不变定义,但电磁场自旋(或轨道)角动量的规范不变定义的概念并不存在.我们发现文献中关于电磁场自旋角动量的规范不变定义是不正确的,这是因为在Dirac-Maxwell理论中表面项不为零,而对于线动量,相应的表面项为零。我们还表明,Belinfante-Rosenfeld张量是不需要获得对称和规范不变的能量动量张量的电子和电磁场的Dirac-Maxwell理论。

英文摘要:

Due to proton spin crisis it is necessary to understand the gauge invariant definition of the spin and orbital angular momentum of the quark and gluon from first principle. In this paper we derive the gauge invariant Noether's theorem by using combined Lorentz transformation plus local gauge transformation. We find that the notion of the gauge invariant definition of the spin (or orbital) angular momentum of the electromagnetic field does not exist in Dirac-Maxwell theory although the notion of the gauge invariant definition of the spin (or orbital) angular momentum of the electron exists. We find that the gauge invariant definition of the spin angular momentum of the electromagnetic field in the literature is not correct because of the non-vanishing surface term in Dirac-Maxwell theory although the corresponding surface term vanishes for linear momentum. We also show that the Belinfante-Rosenfeld tensor is not required to obtain symmetric and gauge invariant energy momentum tensor of the electron and the electromagnetic field in Dirac-Maxwell theory.

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